1. Field of the Invention
This invention relates generally to apparatus for selectively recovering or collecting scrap metal of a given type such as aluminum containers and for compensating depositors of such scrap based on the weight of the metal so collected.
2. Description of the Prior Art
Systems for selectively collecting scrap metal are well known, and U.S. Pat. Nos. 4,179,018 and 4,257,511 issued to John H. Miller are exemplary.
These patents disclose apparatus in which non-returnable aluminum cans such as are used to package soft drinks and malt cereal beverages are segregated from other material such as tin plated steel cans that may be deposited in the apparatus. A start button or switch is pushed by the depositor to start the operation of the apparatus. The deposited materials are conveyed by a conveyor belt to a magnetic separation portion of the apparatus which separates magnetic, ferrous materials such as tin plated steel cans from non-magnetic materials and stores the ferrous materials in a storage bin. However, non-magnetic materials are collected at the bottom of a pneumatic classifier conveyor which transports the aluminum, non-ferrous metal container to a crusher. The materials so transported are crushed and weighed. After weighing, the crushed aluminum is conveyed by a pneumatic stacker conveyor and deposited into an inclined storage location at the top of the apparatus.
The apparatus is provided with a compensation dispenser which dispenses coins, tokens, or other symbols of value, the amount or value of which is determined by the weight of the non-ferrous materials that pass through the crusher and are weighed by the weighing means during operation of the collection apparatus.
This type of apparatus is designed to be unattended and is frequently placed in parking lots of shopping centers where it is easy for persons who patronize the retail stores to dispose of cans.
The recovered aluminum from this source saves energy and raw materials while simultaneously reducing the problems associated with the disposing of such cans after their contents have been consumed. While the present price of tin plated steel cans makes it almost impossible to compensate for them, their collection is of some intrinsic value insofar as cleaning up the environment is concerned. Notwithstanding, a depositor is notified that he will not be compensated for a tin plated steel can.
In copending application Ser. No. 211,739 filed Dec. 1, 1980, now U.S. Pat. No. 4,402,391, issued Sept. 6, 1983, there is described an improved metal collection apparatus for collecting selected metals such as aluminum. The apparatus includes means for detecting false jams, improved compensation means, and better diagnostics through the use of a smart digital controller. The teachings of this application are hereby incorporated by reference. Unfortunately, the apparatus disclosed has several drawbacks. First, field results have indicated that the present apparatus does not adequately weigh the deposited material. It has been shown that under the best of conditions, the present apparatus will weigh to an accuracy of no greater than 95%; however, many weights and measure codes require a greater accuracy (i.e. at least 98%). Furthermore, field failure of the scale dump solenoid had resulted in failure to compensate a depositor for cans deposited. The existing systems require a great deal of service and maintenance, and their throughput has been somewhat limited. Furthermore, these existing systems do not permit the addition of new features without changing the components within the existing controller.
Untrained service personnel tend to operate the system in such a manner as to damage the solid state relays, and there is a tendency on their part to calibrate the system even when such calibration is not required. In the existing system, there is no mechanism for insuring that the pay out equals the advertised price per pound.